Flat display apparatus with laminated optical filter

ABSTRACT

An optical filter  17  is attached to the display screen surface of a flat display panel  3  of a flat display apparatus. The optical filter  17  is constituted of a lamination of an electromagnetic-wave blocking sheet  17 A, an infrared-radiation absorbing and color-tone correcting sheet  17 B and an ambient light antireflective sheet  17 C.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the structure of flat display apparatuses.

The present application claims priority from Japanese Applications No.2002-357617 and No. 2003-356388, the disclosures of which areincorporated herein by reference.

2. Description of the Related Art

A flat display apparatus is equipped with a slim, flat display panel,such as a plasma display panel. (hereinafter referred to as “PDP”), afield emission display panel (hereinafter referred to as “FED”), and thelike.

For example, the PDP is structured such that a pair of front and backsubstrates are placed opposite in parallel to each other with adischarge space in between and the periphery of the discharge space issealed.

More specifically, a reflection-type AC PDP has a plurality of rowelectrode pairs formed on the inner surface of the front substrate forthe creation of a surface discharge (display discharge), and adielectric layer covering the row electrode pairs. Further, on the innersurface of the back substrate facing the front substrate, a plurality ofcolumn electrodes are arranged in a direction at right angles to the rowelectrode pairs for the creation of a selection discharge between thecolumn electrode and one row electrode in each row electrode pair, and acolumn electrode protective layer covers the column electrodes. Betweenthe front substrate and the back substrate, a partition wall is formedfor partitioning the discharge space into discharge cells, and phosphorlayers of the three primary colors (i.e. red, green and blue colors) arerespectively formed in all the discharge cells with the red, green andblue colors arranged in order.

FIG. 1 is a sectional side view illustrating a conventional flat displayapparatus with a flat display panel such as the foregoing PDP mounted.

The conventional display apparatus has a flat display panel 3 which isfixed by an adhesive sheet 4 to the front surface (the upward surface inFIG. 1) of a chassis 2 seated forward of a rear case 1.

A frame 5 is attached to the front peripheral edge of the chassis 2 andsurrounds the flat display panel 3. The frame 5 has an inner flange 5Aformed in its front end. A front filter (panel protective plate) 7 ismounted on a gasket 6 placed on the front face of the inner flange 5A,and secured by a fitting 8.

FIG. 1 shows a front case 9 of the display apparatus.

FIG. 2 is a schematic side view illustrating the structure of the frontfilter (panel protective plate) 7 of the display apparatus.

In FIG. 2, the front filter (panel protective plate) 7 is constructed ofan electromagnetic-wave blocking layer (conductive mesh) 7B formed on aglass substrate 7A; an antireflective layer 7C formed on theelectromagnetic-wave blocking layer 7B; and an infrared-radiationabsorbing and color-tone correcting layer 7D formed on the back surfaceof the glass substrate 7A.

Such a conventional flat display apparatus is described in JapanesePatent Laid-open application No. Hei.11-219122.

As described hitherto, conventional flat display apparatuses have afront filter (panel protective plate) placed forward of the flat displaypanel. The front filter is structured such that a film for preventingthe reflection of ambient light and films for blocking electromagneticwaves and infrared radiation generated from the flat display panel areattached to a glass substrate. This structure makes the front filtervery expensive. Therefore the conventional flat display apparatuses havethe problem of increased production costs.

SUMMARY OF THE INVENTION

It is an object of the present invention to solve the problem associatedwith the conventional flat display apparatuses as described above.

More specifically, an object of the present invention is to provide aflat display apparatus capable of reducing production costs.

To attain the object, the present invention provides a flat displayapparatus having a flat display panel. The flat display apparatus hasthe feature of including a protective sheet attached to the displayscreen surface of the flat display panel.

With the flat display apparatus according to the present invention, theprotective sheet is attached integrally to the display surface of theflat display panel. Hence the elimination of the conventional need forproviding, independently of the flat display panel, a protective panelfor protecting the display surface of the flat display panel isachieved, and therefore a reduction in the number of parts and asimplification in the structure for supporting a flat display panelbecomes possible, thus reducing production costs.

These and other objects and features of the present invention willbecome more apparent from the following detailed description withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional side view illustrating the structure of aconventional flat display apparatus.

FIG. 2 is a schematic side view illustrating the structure of aconventional front filter.

FIG. 3 is a sectional side view illustrating an embodiment according tothe present invention.

FIG. 4 is a schematic side view illustrating the structure of an opticalfilter in the embodiment.

FIG. 5 is a plan view of the optical filter in the embodiment.

FIG. 6 is a plan view illustrating another type of the optical filter.

FIG. 7 is a plan view illustrating yet another type of the opticalfilter.

FIG. 8 is a plan view illustrating still another type of the opticalfilter.

FIG. 9 is a side view of the optical filter in FIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments according to the present invention will bedescribed below in detail with reference to the accompanying drawings.

FIG. 3 is a sectional side view illustrating a first embodiment of theflat display apparatus according to the present invention.

In FIG. 3 the same structural components as those in the conventionalapparatus described in FIG. 1 are designated by the same referencenumerals as those in FIG. 1.

The flat display apparatus in the first embodiment has a flat displaypanel 3 supported on a chassis 2 by means of an elastic sheet 14. Theelastic sheet 14 is formed of a foam material such as foam rubber of a30 or less degrees hardness which is capable of absorbing the distortionoccurring when mounting and the heat dissipated. To the display screensurface of the flat display panel 3, an optical filter 17 is attached asa protective sheet.

As schematically illustrated in FIG. 4, the optical filter 17 is formedby laminating an infrared-radiation absorbing and color-tone correctingsheet 17B on an electromagnetic-wave blocking sheet 17A, and furtherlaminating an ambient-light antireflective sheet 17C on theinfrared-radiation absorbing and color-tone correcting sheet 17B.

The length and width dimensions of the infrared-radiation absorbing andcolor-tone correcting sheet 17B and the ambient-light antireflectivesheet 17C are somewhat smaller than those of the electromagnetic-waveblocking sheet 17A. As illustrated in FIG. 5, the peripheral edge of theelectromagnetic-wave blocking sheet 17A projects outward from the outeredge of the infrared-radiation absorbing and color-tone correcting sheet17B and ambient-light antireflective sheet 17C, so that the metalpattern layer of the electromagnetic-wave blocking sheet 17A is exposedto form an earth connecting part as will be described later.

The optical filter 17 is attached directly to the flat display panel 3by adjoining the electromagnetic-wave blocking sheet 17A to the displaypanel 3 by use of a filter-laminating adhesive material 18.

The filter-laminating adhesive material 18 used for attaching theoptical filter 17 to the flat display panel 3 is made of an acrylic-typeor a silicon-type transparent material and has a refractive indexdiffering by 0.2 or less from the refractive index or each of therefractive indexes of one or both of the optical filter 17 and thesubstrate (the front glass substrate in PDPs) constituting the displayscreen of the flat display panel 3, for example, it has a refractiveindex ranging from 1.4 to 1.6.

Further, the filter-laminating adhesive material 18 used has an adhesivestrength of 3 kgf/inch or less when being vertically detached.

The optical filter 17 with the filter laminating adhesive material 18 isdesigned to be greater than or equal to 0.5 mm thick.

The flat display panel 3 having the optical filter 17 attached to thedisplay side surface is supported on a chassis 2. A frame 15 is attachedto the front-face peripheral edge of the chassis 2 and has an innerflange 15A formed in its front end. The inner flange 15A makes contactwith an electrically-conductive gasket 16 adjoining the area of theoptical filter 17 in which the electromagnetic-wave blocking sheet 17Ais exposed, so as to sandwich the gasket 16 between itself and theoptical filter 17, thereby clamping the flat display panel 3 to thechassis 2.

In place of the gasket, a spring member may be used.

Reference numeral 9 in FIG. 3 denotes a front case of the displayapparatus.

Because the optical filter 17 is integrally attached to the displayscreen surface of the flat display panel 3, the flat display apparatusaccording to the present invention does not need a protective panelprovided independently of the flat display panel 3 for protecting thedisplay screen surface of the flat display panel 3 as in theconventional techniques, so that the number of parts is decreased andthe supporting structure for the flat display panel 3 is simplified tomake low costs of production possible.

Further, the flat display apparatus is designed such that the opticalfilter 17 is attached directly to the display surface of the flatdisplay panel 3, and the refractive index of the filter laminatingadhesive material 18 used for attaching the optical filter 17 isdetermined to differ by 0.2 or less from the refractive index of theoptical filter 17 or the substrate which constitutes the display surfaceof the flat display panel 3, for example in a range of from 1.4 to 1.6so as to be approximately equal to the refractive index of the glasssubstrate constituting part of the flat display panel 3. This designeliminates the reflection (about 8 percent) of the emitted light fromthe flat display panel 3 which occurs due to an air space producedbetween a flat display panel and a protective panel in the conventionaldisplay apparatuses, thereby making possible to improve the brightnessand to prevent the contrast deterioration caused by the rebounding ofthe reflected light to the non-light emission area of the display panel.

More specifically, in the conventional display apparatuses having an airspace produced between the flat display panel and the protective panel,generally, a little over 8 percent of the light generated in the flatdisplay panel reflects off the interfaces of the flat display panel andprotective panel to the air space and returns to the inside of thepanel. At this point, the returning light is diffusely reflected light,and therefore it may illuminate a not-light emission section adjacent tothe light emission section of the panel.

PDPs, in particular, include a phosphor layer formed in the panel. Thereflectance of the phosphor layer is the order of 30 percent, andtherefore the phosphor layer reflects the returning light (i.e. thereflected light from the interface of the flat display panel or theprotective panel). Because of this reflection, it appears that lightemission is caused from the not-light emission section as well as thelight emission section. Hence the outline of the light emission sectionis blurred, leading to a risk of losing the vigor and quality of animage to be displayed.

Further, recently, for the flat display panels, attempt has been made toreduce the black luminance, but the reflection of the returning light asdescribed above may affect the reducing effectiveness of the blackluminance to decrease the reducing effectiveness.

In the aforementioned flat display apparatus, the interfaces of the flatdisplay panel 3 and the optical filter 17 are attached to each other bythe filter laminating adhesive material 18 having the refractive indexdiffering by 0.2 or less from the refractive index of the flat displaypanel 3 and optical filter 17. For this reason, the reflection of lightoff the interfaces is suppressed, leading to the prevention of loss ofvigor and quality of an image, and also the prevention of a decrease inthe reducing effectiveness of the black luminance in regard to the flatdisplay panels attempted to reduce the black luminance.

For a further increase in the foregoing effectiveness of preventinglowering in the vigor and quality of an image and of preventing adecrease in a reduction ratio of the black luminance, when the flatdisplay panel 3 is a PDP, the driving control is performed on adischarge, e.g. a decrease in the intensity of a discharge, a reductionin the number of discharges generated, and the like, such that aluminance of 1 cdm² or less is provided by a discharge (e.g. apreliminary discharge such as a reset discharge, a priming discharge, anaddressing discharge and the like which are caused without having directbearing on the displaying) except the display discharge for lightemission for forming an image.

Further, the foregoing flat display apparatus uses, for thefilter-laminating adhesive material 18, a material of an acrylic-type ora silicon-type having an adhesive strength of 3 kgf/inch or less whenbeing vertically detached, to make it possible to separate the flatdisplay panel 3 and the optical filter 17 for repair without damagingthe bases of the flat display panel 3 and the optical filter 17.

Still further, the determination of a 0.5 or more mm thickness for theoptical filter 17 including the filter-laminating adhesive material 18makes it possible to maintain a shock absorbing property against a shockfrom the outside, and to prevent fracture of the flat display panel.

Yet further, the lamination of the optical filter 17 with theelectromagnetic-wave blocking sheet 17A side located adjacent to theflat display panel 3 results in provision of a relatively stable shieldmember interposed between the flat display panel 3 and theinfrared-radiation absorbing and color-tone correcting sheet 17B, whichincludes dyes tending to suffer degradation from heat or light. Thisinterposition makes possible to lessen the effect of the heat and lightproduced from the flat display panel upon the infrared-radiationabsorbing and color-tone correcting sheet 17B.

Note that by providing a transmittance-reducing component between theelectromagnetic-wave blocking sheet 17A and the flat display panel 3, arelaxation of the acceptable standard of appearance relating toirregular blackening of the electromagnetic-wave blocking sheet 17A andthe like becomes possible.

Further, the electromagnetic-wave blocking sheet 17A of the opticalfilter 17 is formed somewhat larger than the infrared-radiationabsorbing and color-tone correcting sheet 17B and ambient lightantireflective sheet 17C which are to be laminated on theelectromagnetic-wave blocking sheet 17A. Therefore the outer peripheraledge of the electromagnetic-wave blocking sheet 17A projects beyond theouter periphery of the infrared-radiation absorbing and color-tonecorrecting sheet 17B and ambient light antireflective sheet 17C. Thus,it is possible to facilitate connecting the electromagnetic-waveblocking sheet 17A to an earth.

Further, the flat display apparatus according to the present inventionis capable of absorbing and lessening an impact force exerted from theoutside, due to the use of a foam material having a hardness of 30 orless degrees for the elastic sheet 14 which is provided for supportingthe flat display panel 3 on the chassis 2.

Still further, in the flat display apparatus according to the presentinvention, the flat display panel 3 is fixed on the chassis 2 by beingclamped between the frame 15 and the chassis 2 by use of interpositionof the conductive gasket 16 without the use of an adhesive sheet as inthe conventional techniques. Accordingly, the recycling and replacementwork on the flat display panel become much easier as compared with aconventional case when the flat display panel 3 is fixed by use of anadhesive sheet.

In addition, the earth connecting part formed on the outer edge of theoptical filter 17 is supported between the conductive gasket 16 and theoptical filter 17. Thus, the fixing of the display panel by the frame 15and the electric connection with the optical filter 17 are achievedsimultaneously. This makes possible a decrease in the number of parts,resulting in the possibility of reducing production costs.

Moreover, in the first embodiment, the order of lamination of theelectromagnetic-wave blocking sheet, the infrared-radiation absorbingand color-tone correcting sheet, and the ambient light antireflectivesheet in the optical filter is not limited to that illustrated in FIG.4. For example, the electromagnetic-wave blocking sheet and the ambientlight antireflective sheet may be laminated in order onto theinfrared-radiation absorbing and color-tone correcting sheet.

FIG. 3 illustrates the structure when the panel 3 is clamped between theframe 15 and the chassis 2 with the interposition of the conductivegasket 16 to be mounted on the chassis 2. However, an adhesive layer maybe provided on each of the front and back surfaces of the foam materialforming the elastic sheet 14, and the panel may be fixed mounted on thechassis by means of the adhesive layers.

FIG. 6 is a plan view illustrating another structure of an opticalfilter in a second embodiment.

An optical filter 27 in illustrated in FIG. 6 includes anelectromagnetic-wave blocking sheet 27A having the width in the verticaldirection greater than the vertical width of an infrared-radiationabsorbing and color-tone correcting sheet 27B and an ambient lightantireflective sheet 27C. Both the upper end and lower end of theelectromagnetic-wave blocking sheet 27A project beyond theinfrared-radiation absorbing and color-tone correcting sheet 27B andambient light antireflective sheet 27C. However, theelectromagnetic-wave blocking sheet 27A has the same width in thehorizontal direction as that of the infrared-radiation absorbing andcolor-tone correcting sheet 27B and the ambient light antireflectivesheet 27C.

The infrared-radiation absorbing and color-tone correcting sheet 27B andambient light antireflective sheet 27C have aligned recesses 27Ba and27Ca formed in the same position in the central portion of each of theright and left ends, so that an end part of the electromagnetic-waveblocking sheet 27A is exposed inside each set of the recesses 27Ba,27Ca.

The optical filter 27 is connected to an earth at the upper and lowerprojecting end portions a1 of the electromagnetic-wave blocking sheet27A and at portions b1 exposed inside the sets of recesses 27Ba, 27Ca.

The structure of the optical filter 27 of the flat display apparatus asdescribed above enables the following manufacturing method: as indicatedby the broken line in FIG. 6, the electromagnetic-wave blocking sheet27A, the infrared-radiation absorbing and color-tone correcting sheet27B and the ambient light antireflective sheet 27C are formed in a stripshape and rolled up in a scroll shape; and the scrolled sheets 27A, 27Band 27C are then unrolled in the strip form and laminated to one another(at this stage, the strip-form infrared-radiation absorbing andcolor-tone correcting sheet 27B and ambient light antireflective sheet27C have already undergone the punching process for forming the recesses27Ba and 27Ca). The adoption of this manufacturing method makes itpossible to significantly reduce the manufacturing costs for the opticalfilter 27.

In the structure illustrated in FIG. 6, the two sets of recesses 27Ba,27Ca are formed respectively in the right and left ends of the laminatedinfrared-radiation absorbing and color-tone correcting sheet 27B andambient light antireflective sheet 27C. However, a set of recesses 27Ba,27Ca may be formed in a single position, or alternatively three or moresets of recesses 27Ba, 27Ca may be formed.

FIG. 7 is a plan view illustrating yet another structure of an opticalfilter in a third embodiment.

In the optical filter 37 illustrated in FIG. 7, an electromagnetic-waveblocking sheet 37A has the same width in the vertical direction as thevertical width of an infrared-radiation absorbing and color-tonecorrecting sheet 37B and an ambient light antireflective sheet 37C.However, the electromagnetic-wave blocking sheet 37A has the width inthe horizontal direction greater than the horizontal width of theinfrared-radiation absorbing and color-tone correcting sheet 37B and theambient light antireflective sheet 37C. Each of the right and left endsof the electromagnetic-wave blocking sheet 37A projects beyond theinfrared-radiation absorbing and color-tone correcting sheet 37B and theambient light antireflective sheet 37C.

The infrared-radiation absorbing and color-tone correcting sheet 37B andthe ambient light antireflective sheet 37C have aligned sets of recesses37Ba, 37Ca formed in their upper and lower ends. An end part of theelectromagnetic-wave blocking sheet 37A is exposed inside each set ofthe recesses 37Ba, 37Ca.

In the structure illustrated in FIG. 7, the two sets of recesses 37Ba,37Ca are formed on each of the upper and lower ends of the laminatedinfrared-radiation absorbing and color-tone correcting sheet 37B andambient light antireflective sheet 37C. However, a set of recesses 37Ba,37Ca, or alternatively three or more sets of recesses 37Ba, 37Ca may beformed in each of the upper and lower ends.

The optical filter 37 is connected to an earth at portions a2 of theelectromagnetic-wave blocking sheet 37A exposed inside the recesses37Ba, 37Ca and at right and left projecting end portions b2 of theelectromagnetic-wave blocking sheet 37A.

FIGS. 8 and 9 are a plane view and a side view illustrating stillanother structure of an optical filter in a fourth embodiment.

As in the case of the optical filter 17 in the first embodiment, theoptical filter 47 in the fourth embodiment has an electromagnetic-waveblocking sheet 47A having vertical and horizontal dimensions somewhatgreater than those of an infrared-radiation absorbing and color-tonecorrecting sheet 47B and an ambient light antireflective sheet 47C.Therefore, the peripheral end of the electromagnetic-wave blocking sheet47A projects beyond the outer periphery of the infrared-radiationabsorbing and color-tone correcting sheet 47B and the ambient lightantireflective sheet 47C, so that the metal pattern layer of theelectromagnetic-wave blocking sheet 47A is exposed to form an earthconnecting part s.

Further, on the surface of the electromagnetic-wave blocking sheet 47Aof the optical filter 47, a black metal film or blacking-treated coating47D is provided, and therefore the earth connecting part s formed on theouter peripheral end portion of the electromagnetic-wave blocking sheet47A takes the so-called full-face electrode form.

An even number of registration marks M are formed in selected positionsof the earth connecting part s for the lamination of the optical filter47 and the flat display panel (FIG. 8 shows two registration marks M inthe lower corners of the optical filter 47, as an example).

The registration mark M is formed by punching a circle-shaped or across-shaped hole, for example, in the electromagnetic-wave blockingsheet 47A.

Thus, due to the black coating 47D formed on the electromagnetic-waveblocking sheet 47A, the optical filter 47 illustrated in FIGS. 8 and 9is capable of suppressing the reflection of ambient light from theelectromagnetic-wave blocking sheet 47A to make it possible to improvethe contrast of an image to be displayed.

The provision of the registration marks M on the optical filter 47 makespossible easy and precise registration when the optical filter 47 islaminated and attached to the flat display panel by use ofimage-processing techniques or the like in the manufacturing process.

A generic concept of the flat display apparatus in the foregoingembodiment is a flat display apparatus including a flat display paneland a protective sheet attached to the display screen surface of theflat display panel.

With a flat display apparatus based on the generic concept, theprotective sheet is attached integrally to the display surface of theflat display panel. Hence the elimination of the conventional need forproviding, independently of the flat display panel, a protective panelfor protecting the display surface of the flat display panel isachieved, and therefore a reduction in the number of parts and asimplification in structure for supporting a flat display panel becomespossible, thus achieving low costs of production.

The terms and description used herein are set forth by way ofillustration only and are not meant as limitations. Those skilled in theart will recognize that numerous variations are possible within thespirit and scope of the invention as defined in the following claims.

1. A flat display apparatus having a flat display panel, comprising: anoptical filter attached to a display screen surface of the flat displaypanel, wherein the optical filter is formed by laminating, in order, anelectromagnetic-wave blocking layer, an infrared-radiation absorbing andcolor-tone correcting layer, and an ambient light antireflective layer,the optical filter being attached to the display screen surface by atransparent adhesive material, wherein the electromagnetic-wave layer,which faces the flat display panel, includes an outer end portionexposed by projecting beyond the infrared-radiation absorbing andcolor-tone correcting layer and the ambient light antireflective layerwhich are formed on the electromagnetic-wave blocking layer, and theexposed portion of the electromagnetic-wave blocking layer forms anearth connecting part, and wherein a black-colored coating is formed ona surface of the electromagnetic-wave blocking layer of the opticalfilter, and wherein registration marks are formed on the black-coloredcoating covering the earth connecting part.
 2. A flat display apparatushaving a flat display panel, comprising: an optical filter attached to adisplay screen surface of the flat display panel, wherein the opticalfilter is formed by laminating, in order, an electromagnetic-waveblocking layer, an infrared-radiation absorbing and color-tonecorrecting layer, and an ambient light antireflective layer, the opticalfilter being attached to the display screen surface by a transparentadhesive material, the electromagnetic-wave layer facing the flatdisplay panel; and a chassis member that supports the flat displaypanel, which is mounted thereon with interposition of an elastic sheet,wherein a Shore hardness of the elastic sheet is equal to or less than30 degrees.